Bomb Radiocarbon - Bumphead
Indo-Pacific bomb radiocarbon dating - bumphead parrotfish
Publication year 2015
Bomb radiocarbon dating of bumphead parrotfish (Bolbometopon muricatum)
Refinements to the methodology of bomb radiocarbon dating made it possible to validate age estimates of the humphead wrasse (Cheilinus undulatus) and bumphead parrotfish (Bolbometopon muricatum). Age for these species has been estimated from presumed annual growth zones in otoliths at ~30 and ~40 years respectively. The validity of these estimates was tested using bomb radiocarbon dating on the small and fragile otoliths of these species, and provided an opportunity to refine the method using advanced technologies — carbonate extractions were made with a New Wave Research micromilling machine (Elemental Scientific Lasers, Bozeman, MT, USA; http://www.nwrlasers.com/milling/micromill/). A regional Δ14C reference record from hermatypic coral cores from the Great Barrier Reef was assembled and Δ14C measurements from extracted otolith cores of adult otoliths were successful. Validated ages supported the accuracy of growth zone derived ages using sectioned sagittal otoliths.
Publication: Refined Bomb Radiocarbon Dating
Refined bomb radiocarbon dating of two iconic fishes of the Great Barrier Reef
Allen H. Andrews, John H. Choat, Richard J. Hamilton and Edward E. DeMartini
Bumphead parrotfish are the largest of the parrotfish family reaching lengths of up to 1.3 m (4 feet). These fish are thought to be capable of reaching an age of 40 years, but these estimates are based on growth zone counting in otoliths and attempts to validate age have been complicated by various factors. Otoliths of this species are very complex and fragile, but proper sectioning has revealed patterns that may be annual. Based on these data, fish otoliths have been selected for bomb radiocarbon dating to provide a temporal basis for these estimates.
The project currently underway is funded by the Species of Concern Program (Department of Protected Resources, NOAA Fisheries) to provide desperately needed age and growth information about this vulnerable species. For more information on what is known about the bumphead parrotfish and why there is concern, see the SOC bumphead parrotfish flyer.
This project is an international effort with colleagues at James Cook University (John Choat) and The Nature Conservancy (Richard Hamilton). Archival and recent collections from the Great Barrier Reef and Solomon Islands (“Bolbo central”) are being used to describe the age and growth of this species to provide a sound basis for preservation efforts. Age, growth and longevity must be understood to make proper management and protection measures throughout its range.
Good stuff on this species at the Australian Museum.
